With demilitarization worldwide, explosive ordnance disposal (EOD) is becoming an ever more-important technology as nations struggle to deal with stockpiles of explosive devices. The most commonly employed method of EOD heretofore has been open burning and destruction of such devices in, for example, open pits in remote areas. However, the potential for unintended consequences especially when dealing with unstable devices, has led to consideration of alternative methods of EOD.
Recovery of the components, such as propellants and warheads, from such devices has not been a priority, and is only attempted when the manufacturing cost or strategic importance of a particular ingredient is sufficiently high to justify the added recovery expense. However, a process enabling recovery and reuse of these components would increase the cost-effectiveness of such processes.
In addition to the inherent danger involved in EOD, emerging pollution control regulations place severe limitations on the open burning and open detonation (OB/OD) of materials classified as hazardous wastes. Methods of disposal which do not involve detonation or atmospheric pollution are therefore needed. To that end, water-jet cutting followed by oxidizer solvation and reclamation using traditional solvent extraction processes have been proposed, however such technologies have not yet proved practicable.
The method disclosed in U.S. Pat. No. 4,854,982 involves the comminution and removal of propellant ingredients from rocket motors, and extraction/recovery of ammonium perchlorate oxidizer or other soluble ingredients with high pressure anhydrous liquid ammonia. Internal gas pressure within the rocket motor must be greater than that of the vapor pressure of ammonia at the demilitarization temperature to maintain ammonia in liquid state throughout the propellant removal process. Likewise, in U.S. Pat. No. 4,909,868, an inert solvent, such as near-critical or supercritical CO.sub.2, is used to extract plasticizers and stabilizers from propellant, explosive or pyrotechnic compositions.
Finally, in U.S. Pat. No. 5,284,995, a process is disclosed whereby nitramine oxidizers from solid propellant is extracted and recovered using liquid ammonia. The propellant is cut into small pieces, oxidizers are liquified with solvent ammonia, insoluble binders are separated and the remainder recompressed to liquify the liquified gas solvent ammonia for reuse.
While the forgoing patents have addressed one problem encountered with the disposal of munitions (treatment of the propellant/explosive materials), heretofore a major problem remained unsolved. That is, how does one actually gain access to the interior of the metal-clad ordnance to treat the hazardous materials therein? Physically cutting the casing, or mechanically boring holes therein carries inherent risks of accidental ignition, detonation or uncontrolled release of chemicals, and it is difficult to thereafter demonstrate complete removal of the hazardous components therein. This issue has been partially addressed in the past with the concept of "acid trepanning"--gaining access to the interior of the casing by boring holes in the casing with an acid composition. Acid trepanning has been considered in the neutralization of various explosives, including trinitrotoluene (TNT), dynamite (nitroglycerine), pentaerythritol tetranitrate (PETN), cyclotrimethylenetrinitramine (RDX), and ammonium nitrate (AN)--however the interaction between the acid and explosive has been of considerable concern.
Mixtures of pure concentrated acid and explosives can be relatively safe, but the presence of certain dissolved species may create problems. For steel-encased ordnance, aqueous nitric acid solutions with hydrogen peroxide has been used in acid trepanning, while for aluminum casing the use of a concentrated hydrochloric acid solution with at least 1M hydrated cupric chloride has been reported.
Such processes have not been demonstrated with chemical weapon stockpiles subject to demilitarization. The only presently practiced process for such weapons is incineration. However, the facilities necessary to incinerate relatively small quantities of chemical weapons at remote sites makes the construction of such facilities uneconomical. Incineration is subject to potential significant release of chemical agents as vapors. For example, incineration of chemical weapons at Johnson Atoll Chemical Agent Disposal System (JACADS) resulted in three atmospheric releases and at Toelle Chemical Agent Disposal Facility (TOCDF) a single release of chemical agents.
In addition to disposal of munitions actually having chemical or other hazardous materials therein, the disposal of a large number of "test rounds" is a matter of increasing concern. Such rounds are typically filled with a liquid (such as ethylene glycol) simulating the liquid chemical agent. Such rounds are considered by some to be hazardous in their own right, because they are susceptible to being refilled and reused. Additionally, when stored with munitions actually containing chemical agents, it is often impossible to distinguish the test rounds from the live rounds, and it is easier to treat the test rounds as hazardous rather than attempt a determination of their actual state of readiness.
The process of the present invention (hereinafter referred to as the MTAD process) has three distinct advantages: 1) minimal mechanical shock to the device, 2) capability of remote operation, and 3) elimination of the container to an inoperative condition.
Therefore, it is an object of the present invention to provide a comprehensive, safe and cost effective method of treating munitions using acid digestion. The process will provide an effective alternative to conventional methods of rendering such ordnance safe and inoperative within the parameters of current international demilitarization treaties.